In 1990, a longitudinal study was begun to determine long-term outcome of graduates from the Neonatal Intensive Care Unit (NICU) in Hidalgo County, Texas. Developmental assessments were performed at 1-, 4-, 9-, 12- and 22-months age. Assessments include measures of infant sensorimotor skills, infant behavior and temperament, and family background. The evaluations at 22-months also included measures of language ability. Our sample includes approximately 100 children. Our samples reflects the population of the region, which is predominantly Mexican American and has the lowest per capita income in the United States. Forty-two percent of our sample speak only Spanish. A control group is being formed which includes children matched in ethnicity and social class to our NICU sample, but which is not at health risk. On measures of sensorimotor ability, preliminary results suggested that infants showed initial delays, but demonstrated a strong "catch-up" to the normal range by 12-and 22-months. However, 48% of infants at 22- months showed significant language delays. Behavior rating suggest that our NICU sample showed relatively high amounts of expressive, social behaviors, but also higher intensities of behavior which required frequent parental attention. The proposed research sets out an agenda for analysis of the longitudinal data collected through the 22-month period. Seven specific classes of research questions are addressed. In addition, a reassessment of the cohort of NICU graduates is proposed when the children are 4 1/2 years old. Related research is reviewed, and hypotheses are advanced to justify measures planned at the 41/2 year test interval which may predict developmental outcome into the school years.